EDEN PRAIRIE, Minn. - Minnesota Vikings left tackle Matt Kalil has been a limited participant in organized team activity practices while recovering from minor knee surgery but is expected to be ready for training camp, a person with knowledge of the procedure told USA TODAY Sports on Thursday.

The person spoke on condition of anonymity because the team hadn't announced the nature of the arthroscopic procedure, which coach Mike Zimmer said was performed "about four or five weeks ago," declining to elaborate.

Kalil, the No. 4 overall pick in the 2012 draft, has been sitting out team drills during OTAs as a precaution. He has started every game over his first two NFL seasons despite at times dealing with a sore back, among other issues.

Kevin Murphy, a Harvard product who spent most of the past two seasons on the Vikings' practice squad, has been working in Kalil's place on the blind side of quarterback Matt Cassel with the No. 1 offense.

Zimmer revealed Thursday that safety Andrew Sendejo also is coming off surgery on his back "not too long ago." Cornerback Josh Robinson (hamstring) and safety Jamarca Sanford (muscle pull) were among the others sitting out. Zimmer said they're day to day.

Running back Adrian Peterson, who is coming off abdominal surgery, has been taking close to a normal workload.

"I'm well enough to go out and perform, and I don't feel like I'm going to injure myself or hurt myself," Peterson said.

The Vikings haven't gotten much of a look at their top rookies in OTAs.

Linebacker Anthony Barr, defensive lineman Scott Crichton and guard David Yankey are barred from the facility because their schools are in session, and quarterback Teddy Bridgewater missed Thursday's practice to attend the NFL Players Association's rookie premiere event in California.